ocd dox markdown edit
(#380)
noticed, got bugged by, then fussily edited some punctuation of param comments in lensing.py docstrings
(#380)
v minor whitespace fix
(#380)
Add LINKFLAGS to CHANGELOG
(#380)
Update demo comments to be clearer about use of image_pos
(#380)
Add check that only one of image_pos or sky_pos is set
(#380)
Merge pull request #403 from GalSim-developers/#380

#380 Change default centering convention for image drawing to be the true center of the image.
Merge branch 'master' into #407